A distributed antenna system (“DAS”) can be used to extend the coverage of a cellular communication system. For example, a DAS can extend coverage to areas of traditionally low signal coverage within buildings, tunnels, or in areas obstructed by terrain features. A DAS can extend coverage by receiving signals from a base transceiver station of a cellular communication system and re-transmitting the signals directly into low-coverage areas.
A DAS can include a master unit in communication with carrier systems, such as base transceiver stations of cellular service providers. The master unit can receive signals from one or more base stations via interface devices. A non-limiting example of an interface device is an interface card. The master unit can include multiple interface cards, each of which receives an analog RF signal from an analog base station. Interface cards can convert the received analog signals into complex digital signals. The complex digital signals from the interface cards can be combined at a backplane of the master unit for transmission to remote antenna units as a serialized data stream. The remote antenna units can be physically separate from the master unit, but in communication with the master unit over a serial link. A remote antenna unit can wirelessly communicate information in the complex digital signals to wireless user devices positioned in a coverage area.
Some base stations output information as digital signals in a standardized format. These base stations communicate the digital signals in the standardized format to a remote radio head. The remote radio head is in direct communication with the base station and can include a high power RF transceiver that processes the digital signals in the standardized format for transmission to a wireless user device.
Digital signals in a standardized format can include data packets formatted according to standardized telecommunication protocols. Non-limiting examples of standardized telecommunication protocols include the Common Public Radio Interface (“CPRI”), the Open Radio Equipment Interface (“ORI”), and the Open Base Station Standard Initiative (“OBSAI”) protocols. Base stations communicating such data to remote radio heads expect a response communication in a conforming format from the remote radio heads to coordinate communication or otherwise. Remote radio heads can be configured to provide the expected response communication. In accordance with a standardized communication protocol, each data packet can include control data for coordinating data communication between the base transceiver station and the remote radio head. Each data packet can also include carrier data, such as voice or other information, that is to be transmitted to a wireless user device.
Current DASs are unable to communicate with base stations that use digital signals in a standardized format. For example, interface cards in a master unit of a DAS are unable to process the digital signals in the standardized format for use by RF transceivers that are remote antenna units of a DAS and are unable to provide a suitable response to the base station providing the signals. Furthermore remote radio heads configured to process digital signals in a standardized format may be unusable as RF transceivers in a DAS.
Accordingly, a DAS capable of processing digital signals in a standardized format is desirable. A DAS capable of communicating with a remote radio head configured to process digital signals in a standardized format is also desirable.